1. Field of the Invention
The present invention relates to an image recording apparatus in which is mounted a recording head that performs recording by ejecting (discharging) a liquid from an energy generating element or by thermal transfer.
The present invention can be applied for apparatuses, such as printers, copiers, facsimile machines for which communication systems are provided, or word processors that incorporate printers, that perform the recording of images on a recording medium, such as paper, thread, fiber, cloth, leather, metal, plastic, glass, wood or ceramics, and for industrial recording apparatuses with which various processors are combined.
"Recording" in this invention is defined not only as the formation on a recording medium of images, such as characters or drawings, that convey meaning, but also as the formation of images, such as patterns, that convey no meaning.
2. Related Background Art
Conventionally, the demand for recording apparatuses that can produce high quality images has increased, and how to improve image quality has been the subject of numerous discussions. For a recording apparatus in which a recording head is moved in one direction when recording images, the precision of the positioning of an image to be recorded is determined by the accuracy with which the recording head itself is positioned. And for the improvement of the image quality, the enhancement of the accuracy with which a recording head is positioned is an extremely important element. Therefore, in a conventional recording apparatus, for a carriage on which is mounted a recording head that records in only one direction, position detection means (e.g., an image scanner) is provided for accurately ascertaining the position of the recording head. Or, at the carriage's home position in the apparatus, optical reading means is provided to detect the position of the recording head. Then, based on the obtained head positioning data, whether the recording position is adequate or whether the recording position must be corrected is determined.
However, in a conventional recording apparatus the recording head, which constitutes the printing means, and the position detection means are arranged separately. Therefore, in a recording apparatus wherein, for example, a head position detection means is provided for a carriage, satisfactory positioning accuracy for the recording head must be obtained by mounting the recording head on the carriage. In order to obtain such accuracy, precision in the sizing of components, such as the carriage and the recording head, must be improved, or a process must be performed for correcting the positioning of the recording head.
In addition, since elements and circuits for detecting the position of the recording head must be formed on the carriage or on the substrate of the apparatus, manufacturing costs will be increased.
From the viewpoint of high quality image recording, highly delicate recording, for improved image density and tone representation, can be performed by producing dots that have variable sizes.
As the resolution of an image is increased, however, extremely high accuracy is needed to position the dots that are formed, and as the number of steps involved in varying the dot sizes is increased, greater dot size accuracy is required.
Thus, when a plurality of recording elements are employed, dot positioning errors and the use of non-uniform dot sizes can result in the deterioration of the image quality.
It is apparent that the demand for increased image quality can not be satisfied merely by improving the accuracy of the positioning of a carriage and a recording head and the accuracy in the production of dot sizes, so that accordingly, the shortcomings attributable to inaccurate dot positioning and to the unstable production of accurately sized dots are not resolved.